Resumo:

Euterpe edulis (juçara palm) occurs in hight density populations in the Atlantic Forest,
but due the illegal exploration of its heart palm is a extinction threaten species. An alternative
for its conservation is the sustainable management of its populations for fruit production. This
study aims to provide measurement and biometric information for the development of a
sustainable management system for fruit harvest. Prediction models for fruit and fruit pulp
production were developed and the structure and natural regeneration of two populations were
studied. The study was carry out in “Sertão do Ubatumirim”, Ubatuba, in the state of São Paulo,
where a banana plantation and a secondary forest were surveyed in the years 2011 and 2012. In
order to develop the fruit prediction models, producing fruit palm trees were monitored
throughout the period of fructification. Height and diameter measurements were taken in these
trees and the ripe fruits were harvested, weighted, pulped and the fruit pulp dry weight was
determined. The light intensity received by each tree was qualitatively determined by a ordinal
scale with 5 levels. Prediction models for fruit biomass and fruit pulp dry weight were fitted by
linear regression. Prediction quantitative variables were diameter (DBH) and height, while
prediction qualitative variables, add to the model as indicator variables, were: forest type
(banana plantation and secondary forest), harvest year (2011 and 2012) and light intensity. The
criteria for selection of the models were adjusted coefficient of determination and the value of
the Akaike Information Criteria (AIC). For the population surveys, circular plots of 14m radius
were located in the study area, and all trees with DBH equal or greater than 5cm were measured
and had its species identified. For the survey of juçara natural regeneration, circular subplots of
4.5m radius, concentric to adult tree plots, were established to enumerate small trees and
saplings, and circular subplots of 3m radius were established to enumerate seedlings and small
seedlings. Mortality rate was estimated of the entire population and adult juçara palms. For each
plant development stage (tree, small tree, sapling, seedling and small seedling), the number of
individuals and the annual change rate were also estimated. Best prediction models for
individual palm tree fruit and fruit pulp production were logarithmic models, and prediction
variable was tree height, followed by the combined variable (squared diameter times height).
There was a clear interaction effect of the quantitative prediction variable (combined variable)
and the qualitative prediction variable year, as indicator variable. In the hight production year,
the quantitative prediction variable was not relevant for fruit and fruit pulp prediction, while in
the low production year, there was a positive relationship between production and the
quantitative prediction variable. Study sites were very different in forest structure and dynamics.
As expected, the secondary forest site had higher species richness than the banana plantation
site, as well lower mortality rate and twice its basal area. Compared to what is expected to
sustainable juçara populations without human influence, both sites showed lower number of
regenerating individuals (seedlings and small seedlings). Over the years, this fact, combined to
the harvest of fruits for fruit pulp production, can represent risk to the sustainability of juçara
populations in the study sites.